This invention relates to vaginal speculums used for at least the examination of at least the cervical area of the vagina. Essentially such speculums comprise a tubular probe able to be inserted into the vaginal barrel through the vaginal orifice, to define a line of sight extending through the orifice, and associated external equipment.
As is well known the examination may be made by the naked eye or by means of an optical or electronic camera.
As is also well known, preferred embodiments of vaginal speculums may also provide access to the interior of the vaginal barrel for surgical instruments, such as, for example, tissue samplers for collecting cells for so called pap smear tests as used to detect the onset of cervical cancer.
To facilitate examination of the cervical area and the operation of such instruments it has been suggested that vaginal speculums should allow for inflation of at least the cervical end portion of the vaginal barrel by air or other transparent fluid. This requires the speculum to seal off at least that part of the vaginal barrel to be inflated, a transparent fluid tight septum or plug within the bore of the speculum to prevent outflow of pressurising fluid therethrough and the provision of fluid supply means for the admission of pressurised fluid either to the bore of the speculum ahead of that septum or plug or directly into the sealed off part of the vaginal barrel.
Thus a fully functional vaginal speculum is a complex instrument comprising not only the actual tubular probe which enters the vagina but also said external equipment which may include a hand piece for manipulation of the probe, an eye piece to enable an operator to aim and position the probe, a light source for illuminating the cervical area, a camera or at least means for attaching a camera, supply means for the supply of pressurised transparent fluid, commonly air, and sealing means for the retention of the air or other fluid under pressure within the vaginal barrel.
It is of course essential for at least the tubular probe to be sterile before it is inserted into the vagina. Thus it is customary for the tubular probe to be readily separable from and attachable to the external equipment, either to permit it being sterilised between operations or, more preferably, disposed of at the end of an operation and replaced by a previously unused probe for the next operation.
International Application PCT/AU97/00732 (Superior Spec Holdings Limited) (International Publication No. WO 98/19590), describes a prior known vaginal speculum displaying embodiments of the various features mentioned above.
That prior art speculum includes a single use, disposable tubular probe furnished with an inflatable seal positioned at the leading end of the probe. In clinical trials of that prior art speculum it proved to be generally satisfactory but it was found that the centralising effect of the seal caused some difficulty in examining off-centre areas of the vaginal barrel. Indeed, in rare instances, the cervix itself may be misplaced to an extent making it difficult to examine.
An object of the present invention is to alleviate the problems associated with a seal at or near the leading end of the tubular probe.
The invention attains that object by providing a vaginal sealing element encircling the tubular probe intermediate its ends, which element is shaped to contact and seal against body tissue defining the vaginal orifice. This positioning of the seal leaves more of the vaginal barrel available for inspection than was the case when using prior known seals and, more importantly, allows more ready positioning of the leading end of the probe, and thus more ready aiming of the line of sight, with respect to the cervix. As the sealing element in speculums according to the invention contacts tissue that is outside the vaginal barrel it is referred to as an external vaginal seal hereinafter even though the tissue in question is not the skin of the woman being examined.
A seal for use in a somewhat analogous situation is disclosed in German Patent Specification No. DE 44 04 253 relating to an anal speculum. In that instance an anal seal in the form of a trumpet mouth or flared skirt having concave sides with a generally radially extending margin is used. In this instance the seal is more fully external than said vaginal external seals characteristic of the present invention, in that at least the radially extending margin of the sealing element contacts the skin surrounding the anus of the person being examined. In experiments leading to the present invention it was found that sealing elements of the shape disclosed in that German specification are not practicable for use in relation to vaginal speculums.
The problems relating to external seals for vaginal speculums arise from the considerable variation in the size and shape of the vaginal orifice as between one woman and another. If a sealing element having a radially projecting margin adapted to contact and seal against the skin around the vaginal orifice were to be used, then that sealing element would practically determine the extent to which the speculum probe enters the vagina. However, because of internal size variation of the vagina from woman to woman, the depth of probing has to be adjusted by the operator to bring the tip of the probe to an appropriate distance from the cervix. While the body size of the woman and the external appearance of the vagina enables an experienced operator to estimate approximately the likely length of probe needed in any instance, the fact remains that exact adjustment of the probe depth cannot be accurately determined before insertion (and consequent contamination preventing re-use of the probe) has been effected. It follows that the seal has to be maintained over a limited range of probe depths, which is incompatible with a seal between a radially extending margin of the sealing element and the external body surface surrounding the vaginal orifice.
The invention overcomes the above mentioned problem by providing a sealing element that is positioned as aforesaid on the tubular probe so as to be external of the vaginal barrel when in use and which seals only against a circumferential zone of the internal tissue defining the vaginal orifice. To that end the sealing element is devoid of a radially extending edge margin and has a sealing surface shaped as a surface of revolution wherein the diameter of the sealing surface increases progressively with axial distance from the leading end of the sealing element and wherein the rate of increase diminishes progressively with said axial distance.
A sealing element according to the invention relies upon the natural resilience of the so-called PC muscle surrounding the vaginal orifice to permit the orifice to expand and contract so as to allow penetration of the sealing element into the orifice and the maintenance of a seal therewith, throughout a limited range of depths of penetration.
Therefore the invention consists in a vaginal speculum of the kind including a tubular probe for penetrating the vagina characterised in that said probe is encircled by an annular sealing element spaced from the leading end of the probe which seals only against a circumferential zone of the internal tissue defining the vaginal orifice and is shaped as a surface of revolution wherein the diameter of the sealing surface increases progressively with axial distance from the leading end of the sealing element and wherein the rate of increase diminishes progressively with said axial distance.
More simply stated, preferred embodiments of the sealing element may be described as a convex dome devoid of a radially extending edge margin, and having a central circular opening through which the tubular probe tightly extends.